This invention relates to a heat radiating apparatus for use in electric and electronic equipment and, more particularly, to a heat radiating apparatus which uses a heat pipe connected to a heat radiating plate and a heat receiving plate via a medium for heat transfer purposes.
On one hand the function of information equipment represented by computers such as personal computers or workstations is improved, on the other hand much smaller and lightweight information equipment is desired. For example, laptop computers which were once-dominant conventional portable computers have transformed into much smaller notebook computers.
The content volume of the housing of the conventional laptop computer is about 15 litters, whereas that of the notebook computer is solely about 5 litters. In view of this fact, the solution of a problem of heat developed inside the computer as well as the size reduction of the computer system have become important.
In general, the notebook computer has an outer dimension as large as A4 size and a thickness of about 6 cm. The computer is comprised of the main unit including a keyboard and a liquid crystal display having a cover structure for covering the upper surface of the main unit. The hinged liquid crystal display can be freely opened or closed with respect to the main unit. On the assumption that the total power consumption of this notebook computer is 25 watts, the main unit consumes about 15 watts, that is, about 60% of the total power, and the liquid crystal display consumes about 10 watts, that is, the remaining 40% of the power.
To radiate heat developing in a semiconductor device such as an computing element in the main unit, a variety of heat sinks or heat radiating materials or apparatuses such as a microheat pump are used in the above mentioned notebook computer. Particularly, most of the heat pipes are comprised of the main body incorporating a heat receiving plate and a heat radiating plate inside or the main body having only a heat radiating plate disposed at a part of the main body so as to be exposed to outside air. The majority of the heat pipes of this type are provided with heat radiating means which is disposed on the bottom surface of the main body.
In the previously mentioned notebook computer, the heat developed resulting from the consumption of a power of 10 watts in the liquid crystal display is radiated from the front and rear surfaces of the liquid crystal display which are directly exposed to the outside air and hence enable relatively effective heat radiation. Contrary to this, the heat developed resulting from the consumption of a power of 15 watts in the main unit is chiefly radiated only from the bottom surface of the main unit. For this reason, there is a limit to the effective radiation of heat, which results in an insufficient heat radiation effect. Further, the bottom surface of the main unit remains in contact with the surface of the desk while the computer is in use. Since the keyboard is placed on top of this main unit, the heat radiated from the main unit may makes fingers or the palms of the hands sweaty, which in turn becomes cause of user discomfort.
When heat is radiated using a conventional heat pipe, the heat pipe does not have a defined outer shape. Unless the heat pipe is large, it will be difficult to improve the heat radiation effect. This hinders the miniaturization of the main unit of the notebook computer.